Field of the Invention
The present invention relates to a connecting rod of an engine having light weight and high rigidity, and superior in moldability.
Description of the Related Art
In an engine such as internal combustion engine of a vehicle, a connecting rod is disposed for connecting a piston and a crankshaft, and the connecting rod has one end having a smaller diameter (small diameter end) connected to the piston and the other end having a larger diameter (large diameter end) connected to a portion eccentric from a rotating shaft of the crankshaft so as to transfer combustion expansion force applied to the piston to the crankshaft.
In a conventional engine, rigidity in a bending direction with respect to a load in a longitudinal direction is ensured by forming a connecting rod in shape of H in section by providing a reinforcing rib to the connecting portion of the connecting rod such as disclosed in Patent Document 1 (Japanese Patent Laid-open Publication No. 2000-337347.
In this technical field, as the engine performance has been improved and operated at high speed operation and high power operation, the reciprocal motion of the piston increases, and as a result, load applied to the connecting rod in its longitudinal direction is repeated and vibration in a twisting direction is liable to be caused. In order to suppress such vibration in the twisting direction, it becomes necessary to further provide a rib to the connecting rod so as to extend in a different direction in addition to the reinforcing rib provided in the conventional technology for increasing the rigidity.
However, addition of such reinforcing rib with no specific reason, the weight of the connecting rod is increased, which leads to increasing in inertia force in reciprocating mass. As a result, the output power is lowered, fuel efficiency becomes worse, vibration is increased, and responsiveness becomes worse, thus being inconvenient.